This invention relates to the metal forming arts, and more particularly to apparatus for the continuous casting of molten metals such as copper, aluminum and alloys thereof.
In wheel-band type continuous casting machines the casting mold is defined between a peripheral groove formed in the casting wheel and an endless flexible band which closes the groove along a portion of its length. In conventional wheel-band type continuous casting machines the band is guided about the casting wheel by a plurality of guide wheels mounted adjacent the casting wheel. The guide wheels are provided with annular flanges which prevent the band from slipping off the guide wheels and assist in restraining the band from deviating from its predetermined path. However, this arrangement has resulted in a great many disadvantages for several years and has restricted the commericial usages of the wheel-band type continuous casting machine. Essentially, the flanges on the guide wheels cause considerable wear and buckling of the edges of the band which, in turn, causes damage to the rim of the casting wheel.
Moreover, in wheel-band type continuous casting machines it is desirable to use a thin band in order to reduce the stresses therein when the band is first flexed in one direction when it passes around the casting wheel and then flexed in the opposite direction when it passes around the guide wheels. Inasmuch as the band is continuously revolving, and therefore repeatedly flexed in one direction and then in the other, the flexural stresses would be reduced and the band life greatly extended by using a thin band. However, because of the necessity in conventional wheel-band continuous casting machines to use flanges on the guide wheels to steer the band, it has been found necessary to use a thick casting band. When thin bands were used in such casting machines, maintained under adequate tension to prevent leakage of the molten metal from the casting mold, the band would rapidly wear along its edges where it contacted the guide flanges. Furthermore, the band has a tendency to climb the flanges as it enters the guide wheels, thus resulting in distortion and tearing of the edges of the band.
Several attempts have been made by the prior art to provide wheel-band type continuous casting machines having flangeless guide wheels. Generally, in the prior art machines of this type, at least one of the guide wheels would be pivotable about an axis perpendicular to its axis of rotation thus providing for steering of the band and maintaining the band centered on the flat, flangeless surfaces of the guide wheels. Such prior art machines are exemplified in U.S. Pat. No. 3,533,463 issued to R. W. Hazelett, U.S. Pat. No. 3,318,367 issued to T. L. Bray U.S. Pat. No. 3,336,972 issued to D. B. Cofer et al.
However, prior art machines of the aforementioned type are both relatively complicated and expensive, and have not been totally effective in maintaining the band perfectly aligned as it travels about the casting wheel.